Facial design and synthesis of Ce doped Co-Ni oxide nanocages with cubic structure for high-performance asymmetric supercapacitors

From the perspective of nano science and nanotechnology, it is very interesting and important to develop a reasonable and practical synthesis route of nanomaterials for production and life. Here, we develop a strategy of hollow cubic metal oxide nanocages. The method was inspired by Pearson’s Hard-Soft-Acid-Base (HSAB) theory, and nanocages with excellent performance were prepared by coordination etching and optimization of reaction conditions. Firstly, Cu2O nanocubes were prepared by redox reaction at room temperature. Then, the hollow cubic NiCo2Ox/CeOy nanocages were obtained by HSAB theory and cerium doping. The nanomaterial has a specific capacitance of up to 1976 F/g at the current density of 1 A/g. In addition, the asymmetric supercapacitor (ASC) prepared with hollow cubic NiCo2Ox/CeOy nanocage as cathode and active carbon as anode exhibits an energy density as high as 37.1 Wh kg−1 at the power density of 375 W kg−1. The capacitance retention rate of the device is 91.5 % after 10,000 cycles. The device can be charged to light up LED lights. These excellent electrochemical properties, due to their unique structure and synergistic effect between materials, indicate the potential application value of hollow cubic NiCo2Ox/CeOy nanocages in high-performance supercapacitors.